<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title>别踩白块</title>
    <style type="text/css">
        #score{
            text-align: center;}

        h2 {
            text-align: center;    }

        div{
            margin: 0 auto;
            width: 100px;
            height: 100px;}

        #main {
            width: 400px;
            height: 400px;
            background: white;
            border: 2px solid gray;
            margin: 0 auto;
            position: relative;
            overflow: hidden;}

        #con {
            width: 100%;
            height: 400px;
            position: relative;
            top: -100px;
            border-collapse:collapse;}

        .row{
            height: 100px;
            width: 100%;}

        .cell{
            height: 100px;
            width: 100px;
            float: left;}

        .black {
            background: black;}
    </style>
</head>
<body>

    <h2>score</h2>
    <h2 id="score">0</h2>
    <div id="main">
        <div id="con"></div>
    </div>
</body>
<script>
    var clock = null;
    var state = 0;
    var speed = 4;

        /*
        *    初始化 init
        */
        function init(){
            for(var i=0; i<4; i++){
                createrow();
            }

            // 添加onclick事件
            $('main').onclick = function(ev){
                judge(ev);
            }

            // 定时器 每30毫秒调用一次move()
                clock = window.setInterval('move()', 30);
        }

        // 判断是否点击黑块
        function judge(ev){
            if(ev.target.className.indexOf('black') == -1){
                // ev.target.className = 'cell red';
                // fail();
                pass;
            }else{
                ev.target.className = 'cell';
                ev.target.parentNode.pass = 1; //定义属性pass，表明此行row的黑块已经被点击
                score();
            }
        }

        // 游戏结束
        function fail(){
            clearInterval(clock);
            confirm('你的最终得分为 ' + parseInt($('score').innerHTML) );
        }

        // 创建div, className是其类名
        function creatediv(className){
            var div = document.createElement('div');
            div.className = className;
            return div;
        }

        // 创造一个<div class="row">并且有四个子节点<div class="cell">
        function createrow(){
            var con = $('con');
            var row = creatediv('row'); //创建div className=row
            var arr = creatcell(); //定义div cell的类名,其中一个为cell black

            con.appendChild(row); // 添加row为con的子节点

            for(var i = 0; i < 4; i++){
                row.appendChild(creatediv(arr[i])); //添加row的子节点 cell
            }

            if(con.firstChild == null){
                con.appendChild(row);
            }else{
                con.insertBefore(row, con.firstChild);
            }
        }

        // 根据id来get DOM元素
        function $(id) {
            return document.getElementById(id);
        }

        // 创建一个类名的数组，其中一个为cell black, 其余为cell
        function creatcell(){
            var temp = ['cell', 'cell', 'cell', 'cell',];
            var i = Math.floor(Math.random()*4);
            temp[i] = 'cell black';
            return temp;
        }

        //让黑块动起来
        function move(){
            var con = $('con');
            var top = parseInt(window.getComputedStyle(con, null)['top']);

            if(speed + top > 0){
                top = 0;
            }else{
                top += speed;
            }
            con.style.top = top + 'px';

            if(top == 0){
                createrow();
                con.style.top = '-100px';
                delrow();
            }else if(top == (-100 + speed)){
                var rows = con.childNodes;
                if((rows.length == 5) && (rows[rows.length-1].pass !== 1) ){
                  //  fail();
                }
            }
        }

        // 加速函数
        function speedup(){
            speed += 2;
            if(speed == 20){
                alert('你超神了');
            }
        }

        //删除某行
        function delrow(){
            var con = $('con');
            if(con.childNodes.length == 6) {
                   con.removeChild(con.lastChild);
               }
        }

        // 记分
        function score(){
            var newscore = parseInt($('score').innerHTML) + 1;
            $('score').innerHTML = newscore;
            if(newscore % 10 == 0){
                speedup();
            }
        }

    init();
</script>
</html>
